Get all user's calendar

Hi:)

I need to get item(vacation) from calendar, but not only my, I need to know when all users has vacation. Can I do that? 

And one more question. I want also get from calendar my event where organizer is "someone". Now I have:

  cView.PropertySet = new PropertySet(AppointmentSchema.Organizer, AppointmentSchema.Start, AppointmentSchema.End);

            FindItemsResults<Appointment> appointments = calendar.FindAppointments(cView);
            foreach (var a in appointments)
            {
                if (a.Organizer != null && a.Organizer.Name == "someone")

...

}

Is any way to do this without getting all appointments? 

Thank you very much for your help:)